Electric hammer



Oct. 30, 1945. F. v. ROSENBROOK ELEQTRIC HAMMER 2 Sheets-Sheet 1 Filed Jan. 22, 1943 g i'fwezaro t,

Oct. 30, 1945.7 F, v. ROSENBROOK ELECTRIC HAMMER Filed Jan. 22, 1943 2 Sheets-Sheet 2 m 6 w k 7, z J 7 Q/ J 6 m J e r 1/ AW Z Il a I! I Z n. J. liiiil li 2 5 v Z 5 ZZ r. 3 f. @@J...6 a L Cg? 9 w w ,3 W/ Z W w m w In- Patented Oct. 30, 1945 UNITED STATES PATENT OFFICE 2,387,771 ELECTRIC HAMMER Freddie V. ltosenbrook, Chicago, Ill. 1 Application January 22, 1943, Serial No. 473,164

7 Claims.

My invention relates to an electric hammer and has particular reference to a hammer to which a cooperating yoke is attached by means of which light, thin metal, such as light sheet metal used in fenders, sheet metal used in-aire plane wings and other parts, and other extremely' light, thin metal can be straightened and worked, so that bumps. bends and the like can be straightened out and the metal restored to its original form.

Another and further object of my invention is the provision of a hammer in which the force of the blows imparted to the metal can be regulated and in which a wide range of force can be applied running from more forceful blows for heavier metal to very light blows which are something more than vibration and in which the blows are delivered quite rapidly, so that sufncient heat is developed through the impact of the blows, coupled with the blows themselves to change the molecular structure of the metal, similar to the condition present when metal is spun into various designs over a form. This result is accomplished without danger of cracking or otherwise injuring or destroying-the sheet form of the metal.

A further object of the invention is the provision of a combined holder and anvil which is large enough to enable the tool to be operated over a fairly large surface-of metal and so designed that the anvil is not rigid but has considerable elasticity or springiness in it and which in that respect closely approximates the situation when an anvil or a dolly is held by hand against a workpiece and a hammer used by hand in the operation of straightening and re-formin'g metal.

I am aware that hammers of this same general type have heretofore been manufactured, vbut generally they have not been successful because the shocks resulting from the operation of the parts v )s so great that they are soon broken in service, and also because the force of the blow delivered is less resilient, more in the nature of a shock blow rather than the resilient light blow akin to that imparted by an operator with a hand hammer. The rapidity of the blows is sufficient to develop considerable heat and can be used in the field or any placewhere a suitable source of power is obtainable, which has a very wide range of adjustments and can be made to perform satisfactorily on the lightest aluminum sheet material to sheet metal such as automobile fender work, and other of the heavier groups of sheet material. I

These and other objects of my invention will .be more fully and better understood by referin which like reference characters refer to like parts throughout. a frame I0 is shown which has a cylindrical portion II at one side thereof,

- with an electric motor l2 of the usual form being provided. The frame ill has a compartment i3 alongside. of the cylindrical portion H within 1 which a part of the operating parts are mounted.

The'frame It has a projection H at one side thereof over which a handle it is fitted, which is held in place over the projection It by a clamp it, with a socket member I! being mounted on the outer end of the handle it for purposes herein'after described. An electric current transmission cord I8 is provided connected to a switch .box I! located in the handle IS, with a switch operating handle 20 being provided by means of which the operator can open or close the electric circuit leading to the motor l2, as may be-desired during the operation of the device.

The motor l2 has a motor shaft 2| extending a gear wheel 25 mounted o n '-a shaft 26' which, in

turn, is-mounted in the frame III. A cammember 21 also is mounted upon" the shaft 26 and secured .to the gear wheel 25 by means of pins 28, 28. so that the cam member rotates as the vgear 25 is driven by the'worm 24. g

A reciprocating hammer 29 ismounted in the cylindrical portion ll of thefram'e Ill, and comprises a body portion 30 which reciprocates in the bore in the cylindrical portion ll of the frame l0, and a stem portion 3| which is provided with a ball end 32 upon which a head 33 is mounted, the head 33. having a recess therein within whi'ch the ball 32 is seated, and which is held in position by a spring member 34 surworkpiece.

is positioned seated against the lower end of the,

portion 32 of the hammer, so that the force 01* the blow delivered by the hammer is partially above the washer 40 during the operation of the hammer, and also serves as an oil groove for proper lubrication of the various operating parts. Mounted in the fram III is a pin 60 upon which a rocker member BI is mounted, this rocker member 6| having an arm 02 extending radially therefrom for engagement with the projections on the cam 21 as it isrOtated, whil extending radially from the rocker member BI is another arm 63 of rounded contour to fit into the recess ll formed in the body portion of the hammer '29 by means of which the hammer 29 is moved by the rotation of the cam 21. The rocker memreceived upon the spring II, with the washer 40 moving inside of the chamber 35 with each.

stroke of the hammer.

An internally threaded foot 4i the externally threaded end of the portion ii 'of the frame In. An internally formed shoulder 42 on the inner wall of the foot 4| is provided having a spring 42 seated thereon, which bears against the lower end of the portion II. The foot 4| serves both as a support as well as a guide for the hammer as it is moved over the This foot is adjustable so that it is fitted over ber ll disposed opposite from arm 83 with respect to pin 60 acting as a fulcrum constitutes a lever oi the first class and results in a compact construction of. the assembly.

may be properly positioned with respect to the v forced the blow desired, depending upon the character of the work to be performed by the hammer, the thickness of the metal, and other matters which come within the Judgment oi the operator. The normal position of the foot will be approximately that shown in the drawings,

which is approximately even with the end 0! the head 23. If a lighter blow is desired, the foot can be extended beyond the end of the head 33,

while if a heavier blow is desired the-foot may be moved so that the head 33 normally projects a short distance out of the foot 4|.

1 At the top of the cylindrical portion II a cylinder chamber 41 is provided, within which is mounted a cup-shaped washer 45 which supports a spring 48. An externally threaded disc 41 is threaded into a gland member 48 internally ,threaded for engagement with the disc 41 and externally threaded for engagement with the internal threads formed on the upper end of the portion ll of the frame iii. A cap 49 is provided having. finger pieces 50, 50 thereon, within which a stud ii is positioned having a rectangular stem 52 which becomes the male member of a rectangular member 53 fixedly connected to the disc 41, so that as the member. is rotated th disc 41, through the operation of the male and female members 52 and 53, respectively, can be rotated, thus moving the disc member 41 inside of the gland 48 and permitting the operator to vary the tension of the spring 48, thus enabling the operator to adjust the hammer to impart a light or a heavy blow to the workpiece during the operation of the hammer. The gland member 48 has an extension 54 at the upper side thereof within which a circumferential channel l5 extends, with a channel 58 being formed in the cap member 48. A spring member 51 normally holds th cap member 48 in engagement with the gland 48 and allows the cap member to rotate freely thereover so .as to provide adjustment for the spring as hereinbefore pointed'out.

The body portion III of th hammer 29 has a transversely extending recess I58 formed therein with a depth of "at least one-third of the diameter of the said body portion with a spiral groove 59 being provided which prevents the trapping of air below the body portion 30 and The yoke is secured atone of its ends to the socket l1 and comprises. a section'l4 having a pin fitted in a bayonet joint in the socket I1, and a second section 88 of pipe generally semicircular in form, with a proiec'ting end 61 to which a connecting member 42 is mounted. An anvil N is mounted thereon by means of a connecting member lll having a head portion ll fitted into a socket formed in the anvil 89, with a' spring-retaining member I2 bein provided. The head end of the connecting member 10 has a circumferential memberfitted therein within which the head II is seated to hold the connecting member 10 in fixed relation with the member 0]. The anvil {9 is so positioned on the head II that it will conform to and automatically position itself in axial alignment with the hammer 29 during the operation of the device. The members 64 and 68 are connected together by means of the hinge l4 and also by means of a toggle connection comprising a toggle link I! connected to a link II having a finger portion 11, which in turn is pivotally mounted by means of a rivet '18 to a bracket 18 welded or otherwise secured to the member 84. The links 15 and I8 are hingedly connected by a pin 80, while the member 15 has a threaded stud 8| secured thereto to which a spring 82 is connected. The spring 82, in turn, is connected to a nut 82 operating upon a bolt 84 hingedly connected to a bracket 85 welded or otherwise secured to the member v66, so that when the toggle is in closed position the anvil 69 is brought into engagement with the hammer and is held in this position by the tension of the springv 82 when the hammer is in position over a workpiece. When it is desired to remove the hammer, the operator grasps the handle 11 and opens the toggle connection so that the member 88 drops away from the side of the workpiece and the hammer can be easily removed from the workpiece when and if desired.

In operation the device is exceedingly simple in that the operator by grasping the handle I! can place the hammer into the desired position over a workpiece and swing the arm 86 on the under side thereof which places the workpiece in position between the anvil 88 and the head 32 of the hammer. The switch 20, being under the operator's fingers, can be closed, starting the motor and rotating the cam member which, in effect as shown in the drawing, lifts the hammer against the spring 48. This spring is compressed until the lever 02 passes over the ends of'the projecting portions of the cam member, and the hammer is driven downwa rd toward the work, part of the force being received by the spring 39 which is compressed, and part of the blow delivered against the workpiece and through the workpiece shock is received upon the resiliently whether flexible or otherwise, and many other factors which enter into this character of work.

For instance, upon highly polished surfaces the hammer head 33 may be provided with a fiber or rubber covering, or a fiber or rubber covering may be provided over the anvil member 69, such as is now common in hand hammers for use in straightening fenders and doing other body work vin connection with repairs to automobiles. The hammer is designed to operate rapidly so thatthe metal is slightly heated by the impact of the blows delivered upon it as the hammer is moved by the workman around the bent portion or over and across it, depending upon the character of the material to be straightened out.

This operation is continued until the vmetal is straightened or re-formed into the condition in which it was before being deformed by accident or otherwise.

While I have herein described and upon, the drawings shown an illustrative embodiment of the invention. it is to be understood that the invention is not limited thereto but may comprehend other constructions, arrangements of parts, details and features without departing.

from the spirit of the invention.

I claim:

a coil spring at the end of the hammer opposite the striking portion for impelling said hammer into striking position, means in said bore between said striking portion and actuating portion comprising a coil spring for cushioning the blow of the hammer and for efl'ecting a recoil thereof in the reverse direction, an electric motor mounted on said frame, cam means driven by said motor, and rockable means in said frame connected to said actuating portion of said hammer and repeatedly operated by said cam means to drive the hammer in the direction of said recoil and against the force of said first coil spring preparatory to the impellingthereof by said spring upon the separation of the camming means from said rockable means.

3. A vibrating hammer assembly comprising a D-shaped frame composed of a substantially straight portion and a substantially semi-circular portion with a pivotal mounting at one meeting point between said portions, a bore at the end of said straight portion opposite said pivotal mounting, a reciprocatinghammer mounted in said bore extending towards the semi-circular 1. In combination with a frame, a hammer Q mounted for reciprocatory movement in the said frame, electrically operated means whereby the said hammer is actuated, a handle on said frame, a support member detachably connected to said handle, an anvil holding and supporting member hingedly secured to the said support member, an anvil on said anvil holding and supporting member, a toggle member secured to said support member and a spring connected to said toggle member and to the said anvil holding and support member, the toggle member and spring spanning the hinged ends; of the said support member and said anvil holding and support member and adapted to resiliently lock the anvil member against a work piece.

2. A rapidly vibrating electric hammer comprising a frame having a bore therein, a reciprocating hammer mounted in said bore comprising a striking portion at one end thereof and an actuating portion at the opposite end thereof, said striking portion including a universally mounted head an anvil cooperating with the striking head of said hammer, means comprising portion of the D-shaped frame, an anvil mounted at said last mentioned portion remote from said pivotal joint, and yielding connecting means extending between said'straight and semi-circular portions of the frame subtending said piv otal jointand closely adjacent thereto for se- I lectively maintaining said anvil closely adjacent .said reciprocating hammer or to rock said anvil relative to hammer to permit the reception and removal of work between the hammer and anvil.

4.- The combination set forth in claim 3 wherein said yielding connecting means comprises a coil spring and a toggle lever assembly.

5. The combination set forth in claim 2 wherein said anvil cooperating with said striking head is also universally mounted for cooperation with said head, and a tubular foot surrounding said striking head with the free extremity thereof being adjustable relative to the head for controlling the effective blows of the head against the anvil with the material being worked upon therebetween.

6. The combination set forth in claim 2 wherein said rockable means connected to the actuating portion of the hammer comprises a lever of mainder of the straight portion adjacent to said pivotal mounting.

' v FREDDIE V. ROSENBROOK. 

